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Two-Hour Elementary Science Fair Project

Oct 17, 2010 | By Harvey Craft

A science project doesn't have to be time-consuming or complicated to demonstrate a scientific concept. This one takes about two hours, including making the poster.

This project is about heat lost due to evaporation. Evaporation occurs when a liquid turns to a gas. Warmer liquids under normal conditions will evaporate faster because their molecules are moving faster. Since they are moving faster they "escape" from the liquid faster carrying heat energy with them and reducing the temperature of the liquid. This why skin feels cooler when water evaporates from it. This also why hot beverages served in Styrofoam cups have lids provided.

Measuring Evaporative Cooling

Not only does the lid prevent spills, but it keeps the fast, "hot" molecules from escaping and removing heat from the liquid. The effect of evaporative cooling can be easily measured.The materials needed are:

Sixteen ounces of water at bath temperature (+-100º F)

2 Styrofoam cups with a capacity of 10 to 12 ounce capacity each

Two thermometers for measuring water temperature of around 100º F

Index card or cut cardboard for cup lid

A three-panel poster

Miscellaneous: colored pencils, markers, a straight edge, scissors, and paper for making a graph

Parents Watch and Supervise Children

The procedure is almost too simple to seem like a good idea, but the most important thing about a science project is the soundness of the scientific principal involved and how well the scientific method is applied. This project compares the cooling rate of two containers of water – one with a lid and one without a lid. The steps are as follows:

Add eight ounces of water to each cup and immediately measure and record temperatures of each cup after temperatures have stabilized – about a minute. It does not matter if the temperatures are not exactly the same, as it is the change that is important. Be careful with the warm water. It should be warm to be well above room temperature – at least thirty to forty degrees. Temporarily cooling the room where the experiment is performed will help increase the temperature range between maximum water temperature and minimum air temperature.

Leave the thermometers in the cups so temperatures can be easily observed and recorded as temperature drops. Poke a small hole in the lid of the covered cup to allow room for the thermometer – it is not a good idea to remove the lid to record the temperature.

Record the temperatures for each cup after two minute intervals being sure to measure each at the same time.

Continue to make measurements at two-minute intervals for twenty to thirty minutes. The data should begin to indicate that the uncovered cup is cooling at a faster rate than the covered one.

After twenty to thirty minutes stop observations and transfer reading to a single line graph showing both sets of data and using different colored lines to represent the different temperatures. Plot the temperature up the vertical axis in single degree tick-marks. Plot the time across the horizontal axis in two-minute tick-marks.

An Attractive Display in Important

Neatness counts. Parents can supervise the child by offering suggestions about arrangement of data. Show both the data table and the resulting graph. State a hypothesis in an "If…then…" format as required by the scientific method. Digital pictures for verifying the procedure as it was performed add a nice touch. The student should make an educated guess as to which cup will cool fastest. Making a correct prediction is nice, but should not affect the grade because in real science mistaken conclusions are as valuable as correct ones.A conclusion should be stated last. A brief discussion of how the information learned can be important in real life helps add meaning to the experiment.

Science projects don't have to be difficult of time-consuming. What is important is the application of the scientific method in the experiment. The actual experiment can be simple and demonstrate some commonly observed scientific phenomenon. This experiment is ideal for elementary school children with supervision by parents to prevent spilling and discomfort from water that may be a little too warm, although one-hundred degrees Farenheit is not going to cause burns. Use the materials above, follow the scientific method, and make an attractive display

About the author:Harvey Craft is a retired educator and former principal, with extensive experience in teaching grades six through to twelve. He is NBPTS certified in Adolescent Science and now spends his time in educational research, consulting, and freelance writing.Click here to contact or read more articles by Harvey Craft.